Circuits for automatically compensating for distortions generated in output signals from a power amplifier are well known. Such circuit configuration are known to include distortion detection circuits. An example of such circuits is shown in the prior art drawings of U.S. Pat. No. 5,126,687, issued to Onada et al. Conventional circuits known prior to the invention of an "Amplifier System for Automatically Minimizing Distortion" by Onada et al. required a sharp cut-off characteristic in a band-elimination filter and unnecessarily optimize operation of control circuits even when the main input signal is small.
Onada et al. disclosed an automatic distortion compensating amplifier system without the problematic requirements just discussed. In the Onada et al. invention, the distortion detection signal attains a difference of a main input signal having no distortion and a reference (no distortion) signal representing the main output signal, while the main input signal and the reference signal are kept in phase and equal in level. A control circuit sends a predetermined output signal to a power amplifier in order to eliminate distortion. This clipping detection feature automatically turns on when the output signal of the amplifier exceeds a predetermined distortion reference signal.
The Onada et al. system nevertheless has some drawbacks. One disadvantage is that the Onada et al. clipping detection once installed cannot be defeated for a primary listener who desires loud and distorted sounds, for example, a loud rock and/or "rap" afficionado. A like disadvantage is the subjective preference of primary listeners that may not find the predetermined reference signal desirable.